@@ -10495,4 +10495,21 @@ keyword_is_decl_specifier (enum rid keyword)
}
}
+/* Check for and warn about self-assignment or self-initialization.
+ LHS and RHS are the tree nodes for the left-hand side and right-hand side
+ of the assignment or initialization we are checking.
+ LOCATION is the source location for RHS. */
+
+void
+check_for_self_assign (location_t location, tree lhs, tree rhs)
+{
+ /* Only emit a warning if RHS is not a folded expression so that we don't
+ warn on something like x = x / 1. */
+ if (!EXPR_FOLDED (rhs)
+ && operand_equal_p (lhs, rhs,
+ OEP_PURE_SAME | OEP_ALLOW_NULL | OEP_ALLOW_NO_TYPE))
+ warning_at (location, OPT_Wself_assign, G_("%qE is assigned to itself"),
+ lhs);
+}
+
#include "gt-c-family-c-common.h"
@@ -957,6 +957,7 @@ extern VEC(tree,gc) *make_tree_vector (void);
extern void release_tree_vector (VEC(tree,gc) *);
extern VEC(tree,gc) *make_tree_vector_single (tree);
extern VEC(tree,gc) *make_tree_vector_copy (const VEC(tree,gc) *);
+extern void check_for_self_assign (location_t, tree, tree);
/* In c-gimplify.c */
extern void c_genericize (tree);
@@ -319,6 +319,10 @@ Wconversion-null
C++ ObjC++ Var(warn_conversion_null) Init(1) Warning
Warn for converting NULL from/to a non-pointer type
+Wself-assign-non-pod
+C++ ObjC++ Var(warn_self_assign_non_pod) Init(0) Warning
+Warn when a variable of a non-POD type is assigned to itself
+
Wsign-conversion
C ObjC C++ ObjC++ Var(warn_sign_conversion) Init(-1)
Warn for implicit type conversions between signed and unsigned integers
@@ -1626,6 +1626,11 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
maybe_warn_string_init (TREE_TYPE (d), init);
finish_decl (d, init_loc, init.value,
init.original_type, asm_name);
+ /* Check for and warn about self-initialization if
+ -Wself-assign is enabled. Don't warn if there is
+ already an error for the initializer. */
+ if (warn_self_assign && DECL_INITIAL (d) != error_mark_node)
+ check_for_self_assign (here, d, init.value);
}
}
else
@@ -5241,7 +5246,13 @@ c_parser_expr_no_commas (c_parser *parser, struct c_expr *after)
code, exp_location, rhs.value,
rhs.original_type);
if (code == NOP_EXPR)
- ret.original_code = MODIFY_EXPR;
+ {
+ ret.original_code = MODIFY_EXPR;
+ /* Check for and warn about self-assignment if -Wself-assign is
+ enabled. */
+ if (warn_self_assign)
+ check_for_self_assign (op_location, lhs.value, rhs.value);
+ }
else
{
TREE_NO_WARNING (ret.value) = 1;
@@ -561,6 +561,10 @@ Wpadded
Common Var(warn_padded) Warning
Warn when padding is required to align structure members
+Wself-assign
+Common Var(warn_self_assign) Init(0) Warning
+Warn when a variable is assigned to itself
+
Wshadow
Common Var(warn_shadow) Warning
Warn when one local variable shadows another
@@ -598,8 +598,14 @@ perform_member_init (tree member, tree init)
tf_warning_or_error);
if (init)
- finish_expr_stmt (cp_build_modify_expr (decl, INIT_EXPR, init,
- tf_warning_or_error));
+ {
+ finish_expr_stmt (cp_build_modify_expr (decl, INIT_EXPR, init,
+ tf_warning_or_error));
+ /* Check for and warn about self-initialization if -Wself-assign is
+ enabled. */
+ if (warn_self_assign)
+ check_for_self_assign (input_location, decl, init);
+ }
}
if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type))
@@ -7103,6 +7103,16 @@ cp_parser_question_colon_clause (cp_parser* parser, tree logical_or_expr)
tf_warning_or_error);
}
+/* A helpfer function to check if the given expression (EXPR) is of POD type.
+ Note that if the expression's type is NULL (e.g. when its type depends on
+ template parameters), we return false. */
+
+static bool
+expr_is_pod (tree expr)
+{
+ return TREE_TYPE (expr) && pod_type_p (TREE_TYPE (expr));
+}
+
/* Parse an assignment-expression.
assignment-expression:
@@ -7158,6 +7168,16 @@ cp_parser_assignment_expression (cp_parser* parser, bool cast_p,
if (cp_parser_non_integral_constant_expression (parser,
NIC_ASSIGNMENT))
return error_mark_node;
+
+ /* Check for and warn about self-assignment if -Wself-assign is
+ enabled and the assignment operator is "=".
+ Checking for non-POD self-assignment will be performed only
+ when -Wself-assign-non-pod is enabled. */
+ if (warn_self_assign
+ && assignment_operator == NOP_EXPR
+ && (warn_self_assign_non_pod || expr_is_pod (expr)))
+ check_for_self_assign (input_location, expr, rhs);
+
/* Build the assignment expression. */
expr = build_x_modify_expr (expr,
assignment_operator,
@@ -14879,6 +14899,10 @@ cp_parser_init_declarator (cp_parser* parser,
`explicit' constructor cannot be used. */
((is_direct_init || !is_initialized)
? LOOKUP_NORMAL : LOOKUP_IMPLICIT));
+ /* Check for and warn about self-initialization if -Wself-assign is
+ enabled. */
+ if (warn_self_assign && initializer)
+ check_for_self_assign (input_location, decl, initializer);
}
else if ((cxx_dialect != cxx98) && friend_p
&& decl && TREE_CODE (decl) == FUNCTION_DECL)
@@ -257,8 +257,8 @@ Objective-C and Objective-C++ Dialects}.
-Woverlength-strings -Wpacked -Wpacked-bitfield-compat -Wpadded @gol
-Wparentheses -Wpedantic-ms-format -Wno-pedantic-ms-format @gol
-Wpointer-arith -Wno-pointer-to-int-cast @gol
--Wredundant-decls @gol
--Wreturn-type -Wsequence-point -Wshadow @gol
+-Wredundant-decls -Wreturn-type @gol
+-Wself-assign -Wself-assign-non-pod -Wsequence-point -Wshadow @gol
-Wsign-compare -Wsign-conversion -Wstack-protector @gol
-Wstrict-aliasing -Wstrict-aliasing=n @gol
-Wstrict-overflow -Wstrict-overflow=@var{n} @gol
@@ -3379,6 +3379,61 @@ definitions, may be found on the GCC readings page, at
This warning is enabled by @option{-Wall} for C and C++.
+@item -Wself-assign
+@opindex Wself-assign
+@opindex Wno-self-assign
+Warn about self-assignment and self-initialization. This warning is intended
+for detecting accidental self-assignment due to typos, and therefore does
+not warn on a statement that is semantically a self-assignment after
+constant folding. Here is an example of what will trigger a self-assign
+warning and what will not:
+
+@smallexample
+@group
+void func()
+@{
+ int i = 2;
+ int x = x; /* warn */
+ float f = 5.0;
+ double a[3];
+
+ i = i + 0; /* not warn */
+ f = f / 1; /* not warn */
+ a[1] = a[1]; /* warn */
+ i += 0; /* not warn */
+@}
+@end group
+@end smallexample
+
+In C++ it will not warn on self-assignment of non-POD variables unless
+@option{-Wself-assign-non-pod} is also enabled.
+
+@item -Wself-assign-non-pod
+@opindex Wself-assign-non-pod
+@opindex Wno-self-assign-non-pod
+Warn about self-assignment of non-POD variables. This is a C++-specific
+warning and only effective when @option{-Wself-assign} is enabled.
+
+There are cases where self-assignment might be intentional. For example,
+a C++ programmer might write code to test whether an overloaded
+@code{operator=} works when the same object is assigned to itself.
+One way to work around the self-assign warning in such cases when this flag
+is enabled is using the functional form @code{object.operator=(object)}
+instead of the assignment form @code{object = object}, as shown in the
+following example.
+
+@smallexample
+@group
+void test_func()
+@{
+ MyType t;
+
+ t.operator=(t); // not warn
+ t = t; // warn
+@}
+@end group
+@end smallexample
+
@item -Wreturn-type
@opindex Wreturn-type
@opindex Wno-return-type
@@ -3554,6 +3609,10 @@ This warning is enabled by @option{-Wall}.
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
+Note that a classic way to avoid @option{-Wunused-variable} warning is
+using @code{x = x}, but that does not work with @option{-Wself-assign}.
+Use @code{(void) x} or @code{static_cast<void>(x)} instead.
+
@item -Wunused-value
@opindex Wunused-value
@opindex Wno-unused-value
@@ -2392,11 +2392,27 @@ combine_comparisons (location_t loc,
If OEP_PURE_SAME is set, then pure functions with identical arguments
are considered the same. It is used when the caller has other ways
- to ensure that global memory is unchanged in between. */
+ to ensure that global memory is unchanged in between.
+
+ If OEP_ALLOW_NULL is set, this routine will not crash on NULL operands,
+ and two NULL operands are considered equal. This flag is usually set
+ in the context of frontend when ARG0 and/or ARG1 may be NULL mostly due
+ to recursion on partially built expressions (e.g. a CAST_EXPR on a NULL
+ tree.) In this case, we certainly don't want the compiler to crash and
+ it's OK to consider two NULL operands equal. On the other hand, when
+ called in the context of code generation and optimization, if NULL
+ operands are not expected, silently ignoring them could be dangerous
+ and might cause problems downstream that are hard to find/debug. In that
+ case, the flag should probably not be set. */
int
operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
{
+ /* If either is NULL, they must be both NULL to be equal. We only do this
+ check when OEP_ALLOW_NULL is set. */
+ if ((flags & OEP_ALLOW_NULL) && (!arg0 || !arg1))
+ return arg0 == arg1;
+
/* If either is ERROR_MARK, they aren't equal. */
if (TREE_CODE (arg0) == ERROR_MARK || TREE_CODE (arg1) == ERROR_MARK
|| TREE_TYPE (arg0) == error_mark_node
@@ -2406,7 +2422,13 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
/* Similar, if either does not have a type (like a released SSA name),
they aren't equal. */
if (!TREE_TYPE (arg0) || !TREE_TYPE (arg1))
- return 0;
+ {
+ /* If the caller chooses to allow the comparison of operands without
+ types, we will continue the comparison only when both of them don't
+ have a type. */
+ if (!(flags & OEP_ALLOW_NO_TYPE) || TREE_TYPE (arg0) || TREE_TYPE (arg1))
+ return 0;
+ }
/* Check equality of integer constants before bailing out due to
precision differences. */
@@ -2418,19 +2440,24 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
because they may change the signedness of the arguments. As pointers
strictly don't have a signedness, require either two pointers or
two non-pointers as well. */
- if (TYPE_UNSIGNED (TREE_TYPE (arg0)) != TYPE_UNSIGNED (TREE_TYPE (arg1))
- || POINTER_TYPE_P (TREE_TYPE (arg0)) != POINTER_TYPE_P (TREE_TYPE (arg1)))
+ if (TREE_TYPE (arg0)
+ && (TYPE_UNSIGNED (TREE_TYPE (arg0)) != TYPE_UNSIGNED (TREE_TYPE (arg1))
+ || POINTER_TYPE_P (TREE_TYPE (arg0))
+ != POINTER_TYPE_P (TREE_TYPE (arg1))))
return 0;
/* We cannot consider pointers to different address space equal. */
- if (POINTER_TYPE_P (TREE_TYPE (arg0)) && POINTER_TYPE_P (TREE_TYPE (arg1))
- && (TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (arg0)))
- != TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (arg1)))))
+ if (TREE_TYPE (arg0)
+ && (POINTER_TYPE_P (TREE_TYPE (arg0)) && POINTER_TYPE_P (TREE_TYPE (arg1))
+ && (TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (arg0)))
+ != TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (arg1))))))
return 0;
/* If both types don't have the same precision, then it is not safe
to strip NOPs. */
- if (TYPE_PRECISION (TREE_TYPE (arg0)) != TYPE_PRECISION (TREE_TYPE (arg1)))
+ if (TREE_TYPE (arg0)
+ && (TYPE_PRECISION (TREE_TYPE (arg0))
+ != TYPE_PRECISION (TREE_TYPE (arg1))))
return 0;
STRIP_NOPS (arg0);
@@ -2455,9 +2482,10 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
if (TREE_CODE (arg0) != TREE_CODE (arg1)
/* This is needed for conversions and for COMPONENT_REF.
Might as well play it safe and always test this. */
- || TREE_CODE (TREE_TYPE (arg0)) == ERROR_MARK
- || TREE_CODE (TREE_TYPE (arg1)) == ERROR_MARK
- || TYPE_MODE (TREE_TYPE (arg0)) != TYPE_MODE (TREE_TYPE (arg1)))
+ || (TREE_TYPE (arg0)
+ && (TREE_CODE (TREE_TYPE (arg0)) == ERROR_MARK
+ || TREE_CODE (TREE_TYPE (arg1)) == ERROR_MARK
+ || TYPE_MODE (TREE_TYPE (arg0)) != TYPE_MODE (TREE_TYPE (arg1)))))
return 0;
/* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
@@ -2490,7 +2518,8 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
return 1;
- if (!HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0))))
+ if (TREE_TYPE (arg0)
+ && !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0))))
{
/* If we do not distinguish between signed and unsigned zero,
consider them equal. */
@@ -2558,8 +2587,9 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
{
CASE_CONVERT:
case FIX_TRUNC_EXPR:
- if (TYPE_UNSIGNED (TREE_TYPE (arg0))
- != TYPE_UNSIGNED (TREE_TYPE (arg1)))
+ if (TREE_TYPE (arg0)
+ && (TYPE_UNSIGNED (TREE_TYPE (arg0))
+ != TYPE_UNSIGNED (TREE_TYPE (arg1))))
return 0;
break;
default:
@@ -2600,11 +2630,14 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
We can have incomplete types for array references of
variable-sized arrays from the Fortran frontent
though. */
- return ((TYPE_SIZE (TREE_TYPE (arg0)) == TYPE_SIZE (TREE_TYPE (arg1))
- || (TYPE_SIZE (TREE_TYPE (arg0))
- && TYPE_SIZE (TREE_TYPE (arg1))
- && operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
- TYPE_SIZE (TREE_TYPE (arg1)), flags)))
+ return (TREE_TYPE (arg0)
+ && (TYPE_SIZE (TREE_TYPE (arg0))
+ == TYPE_SIZE (TREE_TYPE (arg1))
+ || (TYPE_SIZE (TREE_TYPE (arg0))
+ && TYPE_SIZE (TREE_TYPE (arg1))
+ && operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
+ TYPE_SIZE (TREE_TYPE (arg1)),
+ flags)))
&& (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg0, 1)))
== TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg1, 1))))
&& OP_SAME (0) && OP_SAME (1));
@@ -7575,8 +7608,8 @@ build_fold_addr_expr_loc (location_t loc, tree t)
OP0. Return the folded expression if folding is successful.
Otherwise, return NULL_TREE. */
-tree
-fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0)
+static tree
+fold_unary_loc_1 (location_t loc, enum tree_code code, tree type, tree op0)
{
tree tem;
tree arg0;
@@ -8223,6 +8256,41 @@ fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0)
} /* switch (code) */
}
+/* Given an expression tree EXP, set the EXPR_FOLDED flag, and if it is
+ a nop, recursively set the EXPR_FOLDED flag of its operand. */
+
+static void
+set_expr_folded_flag (tree exp)
+{
+ EXPR_FOLDED (exp) = 1;
+
+ /* If EXP is a nop (i.e. NON_LVALUE_EXPRs and NOP_EXPRs), we need to
+ recursively set the EXPR_FOLDED flag of its operand because the
+ expression will be stripped later. */
+ while ((CONVERT_EXPR_P (exp)
+ || TREE_CODE (exp) == NON_LVALUE_EXPR)
+ && TREE_OPERAND (exp, 0) != error_mark_node)
+ {
+ exp = TREE_OPERAND (exp, 0);
+ EXPR_FOLDED (exp) = 1;
+ }
+}
+
+/* Fold a unary expression of code CODE and type TYPE with operand
+ OP0. Return the folded expression if folding is successful.
+ Otherwise, return NULL_TREE.
+ This is a wrapper around fold_unary_1 function (which does the
+ actual folding). Set the EXPR_FOLDED flag of the folded expression
+ if folding is successful. */
+
+tree
+fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0)
+{
+ tree tem = fold_unary_loc_1 (loc, code, type, op0);
+ if (tem)
+ set_expr_folded_flag (tem);
+ return tem;
+}
/* If the operation was a conversion do _not_ mark a resulting constant
with TREE_OVERFLOW if the original constant was not. These conversions
@@ -9328,8 +9396,8 @@ get_pointer_modulus_and_residue (tree expr, unsigned HOST_WIDE_INT *residue,
Return the folded expression if folding is successful. Otherwise,
return NULL_TREE. */
-tree
-fold_binary_loc (location_t loc,
+static tree
+fold_binary_loc_1 (location_t loc,
enum tree_code code, tree type, tree op0, tree op1)
{
enum tree_code_class kind = TREE_CODE_CLASS (code);
@@ -13170,6 +13238,22 @@ fold_binary_loc (location_t loc,
} /* switch (code) */
}
+/* Fold a binary expression of code CODE and type TYPE with operands
+ OP0 and OP1. Return the folded expression if folding is
+ successful. Otherwise, return NULL_TREE.
+ This is a wrapper around fold_binary_1 function (which does the
+ actual folding). Set the EXPR_FOLDED flag of the folded expression
+ if folding is successful. */
+tree
+fold_binary_loc (location_t loc,
+ enum tree_code code, tree type, tree op0, tree op1)
+{
+ tree tem = fold_binary_loc_1 (loc, code, type, op0, op1);
+ if (tem)
+ set_expr_folded_flag (tem);
+ return tem;
+}
+
/* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
of GOTO_EXPR. */
@@ -13206,9 +13290,9 @@ contains_label_p (tree st)
OP0, OP1, and OP2. Return the folded expression if folding is
successful. Otherwise, return NULL_TREE. */
-tree
-fold_ternary_loc (location_t loc, enum tree_code code, tree type,
- tree op0, tree op1, tree op2)
+static tree
+fold_ternary_loc_1 (location_t loc, enum tree_code code, tree type,
+ tree op0, tree op1, tree op2)
{
tree tem;
tree arg0 = NULL_TREE, arg1 = NULL_TREE, arg2 = NULL_TREE;
@@ -13559,6 +13643,23 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
} /* switch (code) */
}
+/* Fold a ternary expression of code CODE and type TYPE with operands
+ OP0, OP1, and OP2. Return the folded expression if folding is
+ successful. Otherwise, return NULL_TREE.
+ This is a wrapper around fold_ternary_1 function (which does the
+ actual folding). Set the EXPR_FOLDED flag of the folded expression
+ if folding is successful. */
+
+tree
+fold_ternary_loc (location_t loc, enum tree_code code, tree type,
+ tree op0, tree op1, tree op2)
+{
+ tree tem = fold_ternary_loc_1 (loc, code, type, op0, op1, op2);
+ if (tem)
+ set_expr_folded_flag (tem);
+ return tem;
+}
+
/* Perform constant folding and related simplification of EXPR.
The related simplifications include x*1 => x, x*0 => 0, etc.,
and application of the associative law.
@@ -194,7 +194,7 @@ compare_and_warn (gimple stmt, tree lhs, tree rhs)
/* Check and warn if STMT is a self-assign statement. */
static void
-warn_self_assign (gimple stmt)
+check_self_assign (gimple stmt)
{
tree rhs, lhs;
@@ -247,7 +247,7 @@ execute_warn_self_assign (void)
FOR_EACH_BB (bb)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- warn_self_assign (gsi_stmt (gsi));
+ check_self_assign (gsi_stmt (gsi));
}
return 0;
new file mode 100644
@@ -0,0 +1,54 @@
+// Test the self-assignemnt detection and warning.
+// { dg-do compile }
+// { dg-options "-Wself-assign" }
+
+class Foo {
+ private:
+ int a_;
+
+ public:
+ Foo() : a_(a_) {} // { dg-warning "assigned to itself" }
+
+ void setA(int a) {
+ a_ = a_; // { dg-warning "assigned to itself" }
+ }
+
+ void operator=(Foo& rhs) {
+ this->a_ = rhs.a_;
+ }
+};
+
+struct Bar {
+ int b_;
+ int c_;
+};
+
+int g = g; // { dg-warning "assigned to itself" }
+Foo foo = foo; // { dg-warning "assigned to itself" }
+
+int func()
+{
+ Bar *bar1, bar2;
+ Foo local_foo;
+ int x = x; // { dg-warning "assigned to itself" }
+ static int y = y; // { dg-warning "assigned to itself" }
+ float *f;
+ Bar bar_array[5];
+ char n;
+ int overflow;
+
+ *f = *f; // { dg-warning "assigned to itself" }
+ bar1->b_ = bar1->b_; // { dg-warning "assigned to itself" }
+ bar2.c_ = bar2.c_; // { dg-warning "assigned to itself" }
+ local_foo = local_foo;
+ foo = foo;
+ foo.setA(5);
+ bar_array[3].c_ = bar_array[3].c_; // { dg-warning "assigned to itself" }
+ bar_array[x+g].b_ = bar_array[x+g].b_; // { dg-warning "assigned to itself" }
+ y = x;
+ x = y;
+ x += 0; // should not warn
+ y -= 0; // should not warn
+ x /= x; // should not warn
+ y *= y; // should not warn
+}
new file mode 100644
@@ -0,0 +1,31 @@
+// Test the handling of expressions that depend on template parameters in
+// self-assignemnt detection.
+// { dg-do compile }
+// { dg-options "-Wself-assign" }
+
+template<typename T>
+struct Bar {
+ T x;
+ Bar operator++(int) {
+ Bar tmp = *this;
+ ++x;
+ tmp = tmp; // { dg-warning "assigned to itself" }
+ return tmp;
+ }
+};
+
+template<typename T>
+T DoSomething(T y) {
+ T a[5], *p;
+ Bar<T> b;
+ b.x = b.x;
+ *p = *p;
+ a[2] = a[2];
+ return *p;
+}
+
+main() {
+ Bar<int> bar;
+ bar++;
+ DoSomething(5);
+}
new file mode 100644
@@ -0,0 +1,35 @@
+// Test how operands_equal_p handles a NULL operand.
+// { dg-do compile }
+// { dg-options "-Wself-assign" }
+
+#include <cstdio>
+
+namespace testing {
+
+class Foo {
+ int f;
+ public:
+ Foo() { printf("Construct Foo\n"); }
+};
+
+class Bar {
+ int b;
+ public:
+ Bar(int x) { printf("Construct Bar\n"); }
+
+ void operator=(const Foo& foo) {
+ printf("Assign Foo to Bar\n");
+ }
+};
+
+}
+
+template <class T>
+void func(T t) {
+ ::testing::Bar(1) = ::testing::Foo(); // used to trigger a segfault
+ ::testing::Foo() = ::testing::Foo();
+}
+
+main() {
+ func(2);
+}
new file mode 100644
@@ -0,0 +1,48 @@
+// Test how self-assignment detection handles constant-folding happening
+// when parsing the RHS or the initializer.
+// { dg-do compile }
+// { dg-options "-Wself-assign" }
+
+class Foo {
+ private:
+ int a_;
+
+ public:
+ Foo() : a_(a_+0) {} // should not warn
+
+ void setA(int a) {
+ a_ = a_ + 0; // should not warn
+ }
+
+ void operator=(Foo& rhs) {
+ this->a_ = rhs.a_;
+ }
+};
+
+struct Bar {
+ int b_;
+ float c_;
+};
+
+int g = g * 1; // should not warn
+
+int func()
+{
+ Bar *bar1, bar2;
+ Foo foo;
+ int x = x - 0; // should not warn
+ static int y = y / 1; // should not warn
+ float *f;
+ Bar bar_array[5];
+
+ *f = *f / 1; // should not warn
+ bar1->b_ = bar1->b_ * 1; // should not warn
+ bar2.c_ = bar2.c_ - 0; // should not warn
+ foo.setA(5);
+ bar_array[3].c_ = bar_array[3].c_ * 1; // should not warn
+ bar_array[x+g].b_ = bar_array[x+g].b_ / 1; // should not warn
+ x += 0;
+ y -= 0;
+ foo = foo;
+ foo.operator=(foo); // should not warn
+}
new file mode 100644
@@ -0,0 +1,38 @@
+// Test -Wself-assign does not warn on self-assignment of non-POD variables.
+// { dg-do compile }
+// { dg-options "-Wself-assign" }
+
+template<typename T>
+class Foo {
+ private:
+ T a_;
+ public:
+ Foo() : a_(a_) {} // { dg-warning "assigned to itself" }
+ void Set() { a_ = a_; }
+};
+
+struct Bar {
+ int b_;
+ int c_;
+ void operator=(Bar& rhs) {
+ this->b_ = rhs.b_;
+ this->c_ = rhs.c_;
+ }
+};
+
+template <typename T>
+void func() {
+ T a;
+ a = a;
+}
+
+main()
+{
+ Foo<Bar> foo;
+ Bar *bar1, bar2;
+ func<int>();
+ foo = foo;
+ bar2 = bar2;
+ bar1 = bar1; // { dg-warning "assigned to itself" }
+ bar2.b_ = bar2.b_; // { dg-warning "assigned to itself" }
+}
new file mode 100644
@@ -0,0 +1,54 @@
+// Test the self-assignemnt detection and warning.
+// { dg-do compile }
+// { dg-options "-Wself-assign -Wself-assign-non-pod" }
+
+class Foo {
+ private:
+ int a_;
+
+ public:
+ Foo() : a_(a_) {} // { dg-warning "assigned to itself" }
+
+ void setA(int a) {
+ a_ = a_; // { dg-warning "assigned to itself" }
+ }
+
+ void operator=(Foo& rhs) {
+ this->a_ = rhs.a_;
+ }
+};
+
+struct Bar {
+ int b_;
+ int c_;
+};
+
+int g = g; // { dg-warning "assigned to itself" }
+Foo foo = foo; // { dg-warning "assigned to itself" }
+
+int func()
+{
+ Bar *bar1, bar2;
+ Foo local_foo;
+ int x = x; // { dg-warning "assigned to itself" }
+ static int y = y; // { dg-warning "assigned to itself" }
+ float *f;
+ Bar bar_array[5];
+ char n;
+ int overflow;
+
+ *f = *f; // { dg-warning "assigned to itself" }
+ bar1->b_ = bar1->b_; // { dg-warning "assigned to itself" }
+ bar2.c_ = bar2.c_; // { dg-warning "assigned to itself" }
+ local_foo = local_foo; // { dg-warning "assigned to itself" }
+ foo = foo; // { dg-warning "assigned to itself" }
+ foo.setA(5);
+ bar_array[3].c_ = bar_array[3].c_; // { dg-warning "assigned to itself" }
+ bar_array[x+g].b_ = bar_array[x+g].b_; // { dg-warning "assigned to itself" }
+ y = x;
+ x = y;
+ x += 0; // should not warn
+ y -= 0; // should not warn
+ x /= x; // should not warn
+ y *= y; // should not warn
+}
new file mode 100644
@@ -0,0 +1,31 @@
+// Test the handling of expressions that depend on template parameters in
+// self-assignemnt detection.
+// { dg-do compile }
+// { dg-options "-Wself-assign -Wself-assign-non-pod" }
+
+template<typename T>
+struct Bar {
+ T x;
+ Bar operator++(int) {
+ Bar tmp = *this;
+ ++x;
+ tmp = tmp; // { dg-warning "assigned to itself" }
+ return tmp;
+ }
+};
+
+template<typename T>
+T DoSomething(T y) {
+ T a[5], *p;
+ Bar<T> b;
+ b.x = b.x; // { dg-warning "assigned to itself" }
+ *p = *p; // { dg-warning "assigned to itself" }
+ a[2] = a[2]; // { dg-warning "assigned to itself" }
+ return *p;
+}
+
+main() {
+ Bar<int> bar;
+ bar++;
+ DoSomething(5);
+}
new file mode 100644
@@ -0,0 +1,35 @@
+// Test how operands_equal_p handles a NULL operand.
+// { dg-do compile }
+// { dg-options "-Wself-assign -Wself-assign-non-pod" }
+
+#include <cstdio>
+
+namespace testing {
+
+class Foo {
+ int f;
+ public:
+ Foo() { printf("Construct Foo\n"); }
+};
+
+class Bar {
+ int b;
+ public:
+ Bar(int x) { printf("Construct Bar\n"); }
+
+ void operator=(const Foo& foo) {
+ printf("Assign Foo to Bar\n");
+ }
+};
+
+}
+
+template <class T>
+void func(T t) {
+ ::testing::Bar(1) = ::testing::Foo(); // used to trigger a segfault
+ ::testing::Foo() = ::testing::Foo(); // { dg-warning "assigned to itself" }
+}
+
+main() {
+ func(2);
+}
new file mode 100644
@@ -0,0 +1,48 @@
+// Test how self-assignment detection handles constant-folding happening
+// when parsing the RHS or the initializer.
+// { dg-do compile }
+// { dg-options "-Wself-assign -Wself-assign-non-pod" }
+
+class Foo {
+ private:
+ int a_;
+
+ public:
+ Foo() : a_(a_+0) {} // should not warn
+
+ void setA(int a) {
+ a_ = a_ + 0; // should not warn
+ }
+
+ void operator=(Foo& rhs) {
+ this->a_ = rhs.a_;
+ }
+};
+
+struct Bar {
+ int b_;
+ float c_;
+};
+
+int g = g * 1; // should not warn
+
+int func()
+{
+ Bar *bar1, bar2;
+ Foo foo;
+ int x = x - 0; // should not warn
+ static int y = y / 1; // should not warn
+ float *f;
+ Bar bar_array[5];
+
+ *f = *f / 1; // should not warn
+ bar1->b_ = bar1->b_ * 1; // should not warn
+ bar2.c_ = bar2.c_ - 0; // should not warn
+ foo.setA(5);
+ bar_array[3].c_ = bar_array[3].c_ * 1; // should not warn
+ bar_array[x+g].b_ = bar_array[x+g].b_ / 1; // should not warn
+ x += 0;
+ y -= 0;
+ foo = foo; // { dg-warning "assigned to itself" }
+ foo.operator=(foo); // should not warn
+}
new file mode 100644
@@ -0,0 +1,38 @@
+// Test -Wself-assign and -Wself-assign-non-pod.
+// { dg-do compile }
+// { dg-options "-Wself-assign -Wself-assign-non-pod" }
+
+template<typename T>
+class Foo {
+ private:
+ T a_;
+ public:
+ Foo() : a_(a_) {} // { dg-warning "assigned to itself" }
+ void Set() { a_ = a_; } // { dg-warning "assigned to itself" }
+};
+
+struct Bar {
+ int b_;
+ int c_;
+ void operator=(Bar& rhs) {
+ this->b_ = rhs.b_;
+ this->c_ = rhs.c_;
+ }
+};
+
+template <typename T>
+void func() {
+ T a;
+ a = a; // { dg-warning "assigned to itself" }
+}
+
+main()
+{
+ Foo<Bar> foo;
+ Bar *bar1, bar2;
+ func<int>();
+ foo = foo; // { dg-warning "assigned to itself" }
+ bar2 = bar2; // { dg-warning "assigned to itself" }
+ bar1 = bar1; // { dg-warning "assigned to itself" }
+ bar2.b_ = bar2.b_; // { dg-warning "assigned to itself" }
+}
@@ -194,7 +194,7 @@ compare_and_warn (gimple stmt, tree lhs, tree rhs)
/* Check and warn if STMT is a self-assign statement. */
static void
-warn_self_assign (gimple stmt)
+check_self_assign (gimple stmt)
{
tree rhs, lhs;
@@ -247,7 +247,7 @@ execute_warn_self_assign (void)
FOR_EACH_BB (bb)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- warn_self_assign (gsi_stmt (gsi));
+ check_self_assign (gsi_stmt (gsi));
}
return 0;
new file mode 100644
@@ -0,0 +1,27 @@
+/* Test the self-assignemnt detection and warning. */
+/* { dg-do compile } */
+/* { dg-options "-Wself-assign" } */
+
+struct Bar {
+ int b_;
+ int c_;
+};
+
+int g;
+
+int main()
+{
+ struct Bar *bar;
+ int x = x; /* { dg-warning "assigned to itself" } */
+ static int y;
+ struct Bar b_array[5];
+
+ b_array[x+g].b_ = b_array[x+g].b_; /* { dg-warning "assigned to itself" } */
+ g = g; /* { dg-warning "assigned to itself" } */
+ y = y; /* { dg-warning "assigned to itself" } */
+ bar->b_ = bar->b_; /* { dg-warning "assigned to itself" } */
+ x += 0; /* should not warn */
+ y -= 0; /* should not warn */
+ x /= x; /* should not warn */
+ y *= y; /* should not warn */
+}
new file mode 100644
@@ -0,0 +1,24 @@
+/* Test how self-assignment detection handles constant-folding happening */
+/* when parsing the RHS or the initializer. */
+/* { dg-do compile } */
+/* { dg-options "-Wself-assign" } */
+
+struct Bar {
+ int b_;
+ float c_;
+};
+
+int g;
+
+int main()
+{
+ struct Bar *bar;
+ int x = x - 0; /* should not warn */
+ static int y;
+ struct Bar b_array[5];
+
+ b_array[x+g].b_ = b_array[x+g].b_ * 1; /* should no warn */
+ g = g + 0; /* should not warn */
+ y = y / 1; /* should not warn */
+ bar->b_ = bar->b_ - 0; /* should not warn */
+}
@@ -398,8 +398,9 @@ struct GTY(()) tree_base {
unsigned packed_flag : 1;
unsigned user_align : 1;
unsigned nameless_flag : 1;
+ unsigned expr_folded_flag : 1;
- unsigned spare : 12;
+ unsigned spare : 11;
/* This field is only used with type nodes; the only reason it is present
in tree_base instead of tree_type is to save space. The size of the
@@ -638,6 +639,13 @@ struct GTY(()) tree_common {
SSA_NAME_IS_DEFAULT_DEF in
SSA_NAME
+
+ expr_folded_flag:
+
+ EXPR_FOLDED in
+ all expressions
+ all decls
+ all constants
*/
#undef DEFTREESTRUCT
@@ -1371,6 +1379,10 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int,
/* In fixed-point types, means a saturating type. */
#define TYPE_SATURATING(NODE) ((NODE)->base.saturating_flag)
+/* Nonzero in an expression, a decl, or a constant node if the node is
+ the result of a successful constant-folding. */
+#define EXPR_FOLDED(NODE) ((NODE)->base.expr_folded_flag)
+
/* These flags are available for each language front end to use internally. */
#define TREE_LANG_FLAG_0(NODE) ((NODE)->base.lang_flag_0)
#define TREE_LANG_FLAG_1(NODE) ((NODE)->base.lang_flag_1)
@@ -5056,7 +5068,10 @@ extern tree fold_fma (location_t, tree, tree, tree, tree);
enum operand_equal_flag
{
OEP_ONLY_CONST = 1,
- OEP_PURE_SAME = 2
+ OEP_PURE_SAME = 2,
+ OEP_ALLOW_NULL = 4, /* Allow NULL operands to be passed in and compared. */
+ OEP_ALLOW_NO_TYPE = 8 /* Allow operands both of which don't have a type
+ to be compared. */
};
extern int operand_equal_p (const_tree, const_tree, unsigned int);
2011-04-22 Le-Chun Wu <lcwu@google.com> gcc/c-family/ChangeLog: * c-common.c (check_for_self_assign): New function. * c-common.h: New function declaration. * c.opt: New option. gcc/ChangeLog: * c-parser.c (c_parser_declaration_or_fndef): Check for self-assign. (c_parser_expr_no_commas): Check for self-assign. * common.opt: New option. * doc/invoke.texi: Documentation for new options. * fold-const.c (operand_equal_p): Allow operands without typres to compare. (fold_unary_loc_1): Renamed from fold_unary_loc. (fold_unary_loc): New wrapper function. (fold_binary_loc_1): Renamed from fold_binary_loc. (fold_binary_loc): New wrapper function. (fold_ternary_loc_1): Renamed from fold_ternary_loc. (fold_ternary_loc): New wrapper function. * tree.h (struct tree_base): New flag for folded expr. (enum operand_equal_flag): New flags. gcc/cp/ChangeLog: * init.c (perform_member_init): Check for self-assign. * parser.c (expr_is_pod): New function. (cp_parser_assignment_expression): Check for self-assign. (cp_parser_init_declarator): Check for self-assign. gcc/testsuite/ChangeLog: * testsuite/g++.dg/plugin/selfassign.c (check_self_assign): Renamed from warn_self_assign. (execute_warn_self_assign): Call a function by its new name. * testsuite/g++.dg/warn/Wself-assign-1.C: New test case. * testsuite/g++.dg/warn/Wself-assign-2.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-3.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-4.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-5.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-non-pod-1.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-non-pod-2.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-non-pod-3.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-non-pod-4.C: Likewise. * testsuite/g++.dg/warn/Wself-assign-non-pod-5.C: Likewise. * testsuite/gcc.dg/plugin/selfassign.c (check_self_assign): Renamed from warn_self_assign. (execute_warn_self_assign): Call a function by its new name.: * testsuite/gcc.dg/wself-assign-1.c: New test case. * testsuite/gcc.dg/wself-assign-2.c: Likewise. -- This patch is available for review at http://codereview.appspot.com/4442075